Semiconductor processing tools often include components designed to distribute process gases in a relatively even manner across a semiconductor substrate or wafer. Such components are commonly referred to in the industry as “showerheads.” Showerheads typically include a faceplate that fronts a semiconductor processing volume in which semiconductor substrates or wafers may be processed. The faceplate may include a plurality of gas distribution ports that allow gas in the plenum volume to flow through the faceplate and into a reaction space between the substrate and the faceplate (or between a wafer support supporting the wafer and the faceplate). In some instances, a showerhead may be configured to distribute two different gases across a semiconductor substrate or wafer in a simultaneous fashion while isolating the gases from each other within the showerhead. The gas distribution ports are typically arranged such that the gas distribution across the wafer results in substantially uniform substrate processing.